Goodwill and Intangible Assets - Schedule of Acquired Intangible Assets, Other than Goodwill (Detail) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Acquired Finite Lived Intangible Assets [Line Items]
Net Carrying Amount	$ 8,001
Core deposit intangibles [Member]
Acquired Finite Lived Intangible Assets [Line Items]
Gross Carrying Amount	14,792	$ 14,792
Accumulated Amortization	8,508	8,049
Net Carrying Amount	$ 6,284	$ 6,743